Answer: A. one
Step-by-step explanation:
To determine the number of triangles Siobhan will need to draw to complete the pyramid, we first need to consider the shape of the pyramid.
A pyramid is a polyhedron with a polygonal base and triangular faces that meet at a common point (the apex). If we view the pyramid from directly above, we will see the shape of the polygonal base, which is a two-dimensional shape. The triangular faces will not be visible in this view.
Therefore, to complete the pyramid seen from directly above, Siobhan only needs to draw one triangle representing the shape of the polygonal base. The answer is A. one.